Apparatus arranged for converting a wheeled vehicle to a tracked vehicle

ABSTRACT

Apparatus arranged for converting a wheeled vehicle to a tracked vehicle by attachment of a continuous track unit, the vehicle comprising a drive hub of the type which is arranged to have an attachable wheel, the continuous track unit replacing the wheel to engage ground in use for movement of the vehicle, the apparatus comprising a mounting portion releasably attachable to the vehicle&#39;s chassis, the mounting portion arranged to substantially surround the drive hub, a support arm for supporting the continuous track unit, and a drive sprocket releasably attachable to the drive hub for transferring torque from the drive hub to the continuous track unit so as to rotate the track in use with the wheel removed and the apparatus attached to the vehicle.

PRIORITY

The present application is related to, claims the priority benefit of,and is a U.S. continuation-in-part patent application of, U.S. patentapplication Ser. No. 15/550,666, filed Aug. 11, 2017, which is relatedto, claims the priority benefit of, and is a U.S. national stage (§ 371)patent application of, PCT Patent Application Serial No.PCT/GB2016/050350, filed Feb. 12, 2016, which is related to, and claimsthe priority benefit of, Great Britain Patent Application Serial No.1502475.5, filed Feb. 13, 2015. The contents of each of theseapplications are hereby incorporated by reference in their entirety intothe present disclosure.

TECHNICAL FIELD

The present invention relates generally to apparatus arranged forconverting a wheeled vehicle to a tracked vehicle, and finds particular,although not exclusive, utility in converting wheeled mini-loaders torun on continuous tracks.

BACKGROUND

Plant manufacturers typically produce mini-loaders with wheels and nottracks as they are not aimed at use on rough and/or soft terrain. Bymini-loaders is meant less than 2 to 5 tonnes in weight un-laden.However, it is useful in some circumstances to use such plant in suchconditions and in this case the use of continuous tracks is better thanwheels. Relatively small (preferably less than 1 metre in length,although other lengths are contemplated) continuous track units may beretro-fitted to such vehicles via the drive hub. However, the vehiclesin question have to be used carefully as the track units can shear-offthe drive hub through rough use, shock loading and the like.

BRIEF SUMMARY

The present invention provides apparatus for retro-fitting theserelatively small continuous track units to wheeled vehicles which may beused more roughly and which can withstand greater shock loading.

In a first aspect, the invention provides apparatus arranged forconverting a wheeled vehicle to a tracked vehicle by attachment of acontinuous track unit, the vehicle comprising a drive hub of the typewhich is arranged to have an attachable wheel, the continuous track unitreplacing the wheel as the driving force of the vehicle, the apparatuscomprising a first portion attachable to the vehicle's chassis, thefirst portion arranged to substantially surround the drive hub, a secondportion including a support arm for supporting the continuous trackunit, the second portion releasably attachable to the first portion, anda drive sprocket releasably attachable to the drive hub for transferringtorque from the drive hub to the continuous track unit so as to rotatethe track in use with the wheel removed and the apparatus attached tothe vehicle, wherein the apparatus is arranged such that once attachedto the vehicle the second portion and drive sprocket are removable, anda wheel is attachable to the drive hub with the first portion stillattached to the support structure of the vehicle.

The vehicle's initially attached wheel typically includes a tyre,possibly pneumatic in nature. The wheel is suitable for running on theground to propel the vehicle.

The chassis includes the vehicle's structural support framework whichmay include a substantially vertical surface to which the first portionis attachable; this substantially vertical surface remaining immobilerelative to the remainder of the vehicle, excluding the drive hub andanything attached thereto. In other words, the chassis does not formpart of the steering apparatus of the vehicle because the vehicle mayhave no steering apparatus (or steering knuckle), as such.

Continuous track units comprise of a support structure for supportingthe idler wheels, and a drive sprocket for rotation of the track. Theweight of the track unit, and the forces imparted on it in use, is borneby the support structure and not the drive sprocket.

Attachment of retro-fittable track units to steering knuckles ofvehicles has been found to be damaging as the structure is not designedfor the additional forces imparted to it by the track units.Accordingly, the apparatus for attaching the track unit's supportstructure is not attached to any part of the steering means of avehicle.

The support arm of the second portion may support the support structureof the continuous track unit. The track unit may at least partiallyrotate, or pivot, about the support arm which is typically arrangedsubstantially horizontally, in use. The second portion may be arrangedto accept a support bracket of the continuous track unit. The secondportion may include fasteners for releasably attaching the support armthereto. The fasteners may comprise nuts and bolts. Alternatively, thesupport arm may be welded to the second portion.

The first portion may be attachable to the chassis by fasteners whichextend parallel with the axis of rotation of the drive hub. Forinstance, bolts may be used passing through holes provided through theside wall of the first portion and through corresponding holes providedin the chassis with nuts located behind the chassis.

The second portion may comprise an annual plate which is releasablyattachable to the first portion via fasteners, such as bolts. The boltsmay pass through holes arranged in the second portion and intocorresponding holes arranged in the outer face of the first portion. Inthis regard, the outer face is taken to mean the face at the axial endof the first portion opposite from the end attached to the chassis.

The fasteners may be arranged circumferentially around the drive hub.The fasteners may be arranged approximately equidistantly around thedrive hub.

This may help to spread any imparted forces avoiding undue stress in anyparticular area.

The drive sprocket may be releasably attachable to the drive hubdirectly or indirectly. In other words an intermediary member may beprovided between the drive hub and the drive sprocket. The intermediarymember may be welded or removably attachable to the drive sprocket.

The wheel may be re-attachable to the drive hub with the first portionstill attached to the support structure of the vehicle because the firstportion is arranged not to extend beyond the outer face of the drive hubsuch that it will not foul the wheel.

The first portion may comprise a substantially cylindrical member. Thediameter of the bore of the cylinder may be only slightly larger thanthe diameter of the drive hub. For instance, it might be in the range of5 to 50 mm greater in radius. Preferably it might be only 5 to 20 mmgreater in radius such that the gap between the outer circumference ofthe drive hub, at its widest point within the bore of the first portion,and the inner surface of the first portion is quite narrow.

The term “drive hub” includes drive motor.

The first portion may have a wall thickness which varies along its axiallength such that it is thicker at the axial end opposite from the endattachable to the vehicle chassis. The thickness may change gradually orbe stepped. The first portion may be formed from a cylinder of mildsteel or aluminium having an initial wall thickness of approximately 20mm. Portions of the wall may be reduced in thickness towards the endwhich attaches to the support structure of the vehicle so as to reduceweight. Portions of the wall may be increased in thickness towards theend opposite from the end which attaches to the support structure so asto increase its strength. The wall may have a step change in thickness,or a tapering so as to fit around the drive hub of the vehicle withoutcontacting it.

In a second aspect, the invention provides a vehicle comprisingapparatus according to the first aspect.

The vehicle may be articulated.

In a third aspect, the invention provides an articulated wheeled vehicleincluding apparatus arranged for converting it to an at least partiallytracked vehicle by attachment of a continuous track unit, the vehiclecomprising a drive hub of the type which is arranged to have anattachable wheel, the continuous track unit replacing the wheel as thedriving force of the vehicle, the apparatus comprising a first portionattached to the vehicle's chassis, the first portion arranged tosubstantially surround the drive hub, a second portion including asupport arm for supporting the continuous track unit, the second portionreleasably attached to the first portion, and a drive sprocketreleasably attached to the drive hub for transferring torque from thedrive hub to the continuous track unit so as to rotate the track in use.

The vehicles may have rigid drive axles such that steering of thevehicle is effected by slewing the two halves of the vehicle, separatedby the articulation joint, relative to one another.

The vehicles may be arranged to lift and carry loads. The vehicles maybe a loader, a fork lift, a tele-handler, or a tool-carrier. The vehiclemay comprise a movable arm. The arm may be telescopic. The vehicle mayhave a weight less than 2 tonnes.

It is possible to convert a wheeled vehicle to a tracked vehicle withalternative apparatus such that in a fourth aspect, the inventionprovides apparatus arranged for converting a wheeled vehicle to atracked vehicle by attachment of a continuous track unit, the vehiclecomprising a drive hub of the type which is arranged to have anattachable wheel, the continuous track unit replacing the wheel toengage ground in use for movement of the vehicle, the apparatuscomprising a mounting portion releasably attachable to the vehicle'schassis, the mounting portion arranged to substantially surround thedrive hub, a support arm for supporting the continuous track unit, and adrive sprocket releasably attachable to the drive hub for transferringtorque from the drive hub to the continuous track unit so as to rotatethe track in use with the wheel removed and the apparatus attached tothe vehicle.

The chassis includes the vehicle's structural support framework whichmay include a substantially vertical surface to which the mountingportion is attachable; this substantially vertical surface remainingimmobile relative to the remainder of the vehicle, excluding the drivehub and anything attached thereto. In other words, the chassis does notform part of the steering apparatus of the vehicle because the vehiclemay have no steering apparatus (or steering knuckle), as such.

Continuous track units comprise of a support structure for supportingthe idler wheels, and a drive sprocket for rotation of the track. Theweight of the track unit, and the forces imparted on it in use, is borneby the support structure and not the drive sprocket. The supportstructure may include an idler carriage comprising two parallel platesheld together by tie bars and to which idler wheels are pivotablymounted.

The mounting portion may comprise a flat plate for abutting against thevehicle's chassis when attached thereto.

The mounting portion may comprise through-holes for bolting it to thevehicle's chassis.

The mounting portion may be attachable to the vehicle's chassis byfasteners which extend parallel with the axis of rotation of the drivehub. For instance, bolts may be used passing through holes providedthrough the side wall of the mounting portion and through correspondingholes provided in the chassis with nuts located behind the chassis.

The mounting portion may be attachable to the chassis by fastenersarranged circumferentially around the drive hub.

The fasteners may be arranged approximately equidistantly around thedrive hub. This may help to spread any imparted forces avoiding unduestress in any particular area.

The mounting portion may be in the form of a plate with a hole in itthrough which the drive hub projects when fitted to a vehicle chassis.In other words, the mounting portion may be an annulus. Alternatively,the mounting portion may be in the form of a plate which has an aperturein it extending to one edge of the plate, the drive hub projectingthrough the aperture with the mounting portion fitted to a vehiclechassis.

The support arm may be arranged to fit into an idler carriage of a trackunit comprising tie-bars, wherein the support arm is arranged to replacean existing tie-bar.

The support arm may be integral with the mounting portion, or releasablyattachable thereto. The apparatus may include gussets welded between thesupport arm and the mounting portion wherein at least two gussets areoriented orthogonally to one another.

The support arm may support the support structure of the continuoustrack unit. The track unit may at least partially rotate, or pivot,about the support arm which is typically arranged substantiallyhorizontally, in use. The support arm may be arranged to accept asupport bracket of the continuous track unit.

The drive sprocket may be releasably attachable to the drive hubdirectly or indirectly. In other words, an intermediary member may beprovided between the drive hub and the drive sprocket. The intermediarymember may be welded or removably attachable to the drive sprocket.

The term “drive hub” may include drive motor.

The support arm may be arranged such that it is off-set to one side of acentre-line passing vertically through the drive hub. For instance, thesupport arm may be arranged such that it is off-set towards the front ofthe vehicle in front of a centre-line passing vertically through thedrive hub. In this way the stability of the vehicle may be enhancedbecause the distance between the front and rear tracks may be increased.Likewise, the support arm on apparatus attached to a rear of the vehiclemay be arranged such that it is off-set towards the rear of the vehiclebehind a centre-line passing vertically through the drive hub.

The support arm may be arranged below the drive hub. This may reduce anyincrease in height of the vehicle being caused through replacement of awheel having a radius less than the distance between the centre of thedrive hub and the bottom of the tracks immediately below.

In a fifth aspect, the invention provides an articulated wheeled vehicleincluding apparatus arranged for converting it to an at least partiallytracked vehicle by attachment of a continuous track unit, the vehiclecomprising a drive hub of the type which is arranged to have anattachable wheel, the continuous track unit replacing the wheel toengage ground in use for movement of the vehicle, the apparatuscomprising a mounting portion releasably attachable to the vehicle'schassis, the mounting portion arranged to substantially surround thedrive hub, a support arm for supporting the continuous track unit, and adrive sprocket releasably attachable to the drive hub for transferringtorque from the drive hub to the continuous track unit so as to rotatethe track in use with the wheel removed and the apparatus attached tothe vehicle.

The vehicle may comprise two units articulated together with anarticulated joint, and comprising rigid drive axles such that steeringof the vehicle is effected by slewing the two units of the vehicle,separated by the articulation joint, relative to one another.

The vehicles may be arranged to lift and carry loads. The vehicles maybe a loader, a fork lift, a tele-handler, or a tool-carrier. The vehiclemay comprise a movable arm. The arm may be telescopic. The vehicle mayhave a weight less than 5 tonnes.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other characteristics, features and advantages of thepresent invention will become apparent from the following detaileddescription, taken in conjunction with the accompanying drawings, whichillustrate, by way of example, the principles of the invention. Thisdescription is given for the sake of example only, without limiting thescope of the invention. The reference figures quoted below refer to theattached drawings.

FIG. 1 is a perspective view of a vehicle converted to includecontinuous track units in place of wheels;

FIG. 2 is a partial view of a vehicle including at least some of theconversion apparatus and the continuous track unit;

FIG. 3 is a schematic plan view of at least some of the conversionapparatus attached to a drive hub with a sprocket attached;

FIG. 4 is a view of a continuous track unit sprocket;

FIG. 5 is a partial view of a sprocket and part of the conversionapparatus; and

FIG. 6 is a schematic plan view of at least some of the conversionapparatus attached to a drive hub with a wheel attached;

FIG. 7 is a schematic plan view of at least some of an alternativeconversion apparatus attached to a drive hub with a sprocket attached;

FIG. 8 is an elevational view of the alternative conversion apparatus ofFIG. 7;

FIG. 9 is a perspective view of part of a vehicle including at leastsome of a different conversion apparatus;

FIG. 10 is a schematic plan view of at least some of the differentconversion apparatus attached to a chassis of a vehicle; and

FIG. 11 is a perspective view of part of a vehicle including thedifferent conversion apparatus.

DETAILED DESCRIPTION

The present invention will be described with respect to certain drawingsbut the invention is not limited thereto but only by the claims. Thedrawings described are only schematic and are non-limiting. Each drawingmay not include all of the features of the invention and thereforeshould not necessarily be considered to be an embodiment of theinvention. In the drawings, the size of some of the elements may beexaggerated and not drawn to scale for illustrative purposes. Thedimensions and the relative dimensions do not correspond to actualreductions to practice of the invention.

Furthermore, the terms first, second, third and the like in thedescription and in the claims, are used for distinguishing betweensimilar elements and not necessarily for describing a sequence, eithertemporally, spatially, in ranking or in any other manner. It is to beunderstood that the terms so used are interchangeable under appropriatecircumstances and that operation is capable in other sequences thandescribed or illustrated herein.

Moreover, the terms top, bottom, over, under and the like in thedescription and the claims are used for descriptive purposes and notnecessarily for describing relative positions. It is to be understoodthat the terms so used are interchangeable under appropriatecircumstances and that operation is capable in other orientations thandescribed or illustrated herein.

It is to be noticed that the term “comprising”, used in the claims,should not be interpreted as being restricted to the means listedthereafter; it does not exclude other elements or steps. It is thus tobe interpreted as specifying the presence of the stated features,integers, steps or components as referred to, but does not preclude thepresence or addition of one or more other features, integers, steps orcomponents, or groups thereof. Thus, the scope of the expression “adevice comprising means A and B” should not be limited to devicesconsisting only of components A and B. It means that with respect to thepresent invention, the only relevant components of the device are A andB.

Reference throughout this specification to “an embodiment” or “anaspect” means that a particular feature, structure or characteristicdescribed in connection with the embodiment or aspect is included in atleast one embodiment or aspect of the present invention. Thus,appearances of the phrases “in one embodiment”, “in an embodiment”, or“in an aspect” in various places throughout this specification are notnecessarily all referring to the same embodiment or aspect, but mayrefer to different embodiments or aspects. Furthermore, the particularfeatures, structures or characteristics of any embodiment or aspect ofthe invention may be combined in any suitable manner, as would beapparent to one of ordinary skill in the art from this disclosure, inone or more embodiments or aspects.

Similarly, it should be appreciated that in the description variousfeatures of the invention are sometimes grouped together in a singleembodiment, figure, or description thereof for the purpose ofstreamlining the disclosure and aiding in the understanding of one ormore of the various inventive aspects. This method of disclosure,however, is not to be interpreted as reflecting an intention that theclaimed invention requires more features than are expressly recited ineach claim. Moreover, the description of any individual drawing oraspect should not necessarily be considered to be an embodiment of theinvention. Rather, as the following claims reflect, inventive aspectslie in fewer than all features of a single foregoing disclosedembodiment. Thus, the claims following the detailed description arehereby expressly incorporated into this detailed description, with eachclaim standing on its own as a separate embodiment of this invention.

Furthermore, while some embodiments described herein include somefeatures included in other embodiments, combinations of features ofdifferent embodiments are meant to be within the scope of the invention,and form yet further embodiments, as will be understood by those skilledin the art. For example, in the following claims, any of the claimedembodiments can be used in any combination.

In the description provided herein, numerous specific details are setforth. However, it is understood that embodiments of the invention maybe practised without these specific details. In other instances,well-known methods, structures and techniques have not been shown indetail in order not to obscure an understanding of this description.

In the discussion of the invention, unless stated to the contrary, thedisclosure of alternative values for the upper or lower limit of thepermitted range of a parameter, coupled with an indication that one ofsaid values is more highly preferred than the other, is to be construedas an implied statement that each intermediate value of said parameter,lying between the more preferred and the less preferred of saidalternatives, is itself preferred to said less preferred value and alsoto each value lying between said less preferred value and saidintermediate value.

The use of the term “at least one” may mean only one in certaincircumstances.

The principles of the invention will now be described by a detaileddescription of at least one drawing relating to exemplary features ofthe invention. It is clear that other arrangements can be configuredaccording to the knowledge of persons skilled in the art withoutdeparting from the underlying concept or technical teaching of theinvention, the invention being limited only by the terms of the appendedclaims.

FIG. 1 is a view of an articulated vehicle 10 converted to includecontinuous track units 15, comprising tracks 20, attached to thevehicle's chassis 25 in place of each of its four wheels. The vehicleincludes a telescopic movable arm 11.

In FIG. 2 the drive hub 25 of the vehicle is shown. The drive hub 25includes a disc 30 which includes bolts for attaching to a wheel rim inthe vehicle's un-converted state. In use, the disc 30 rotates thusrotating the wheel rim.

A first portion 40 of the apparatus has been attached to the supportstructure of the vehicle. The first portion is in the form of a cylinderand it surrounds the drive hub 25. The first portion remains stationaryand the disc 30 of the drive hub 25 may rotate relative to it.

A second portion 55 of the apparatus in the form of a flange attached tothe lower half of the axial end (furthest from the support structure) ispartially visible. It is attached to the end of the first portion bywelding but it may be affixed by nuts and bolts.

A support bracket 50 is attached to this second portion by means of nutsand bolts. The support bracket 50 includes a rocker bar 80 about whichthe continuous track unit is partially supported and about which it mayat least partially rotate. Some of the idler wheels 90 are visiblewithin their own support structure 100 which is pivotably connected tothe rocker bar 80. A portion of the track 110 is visible; however, thesprocket is not shown for the sake of clarity.

The second portion 55 includes metal protrusions 60, 70 welded to itsfront (outer) face which lie against the sides of the support bracket50. The rotational movement of the support bracket 50 about an axisparallel to the rotational axis of the drive hub/disc 25, 30 is thusimpeded by these projections 60,70 in addition to that provided by thenuts and bolts.

The recess may be 4 to 6 mm in depth, although other depths arecontemplated. The recess may more firmly locate the bracket with thesecond portion and prevent the bracket moving relative to the secondportion such that the attachment bolts do not shear. In this way, shockloading of the vehicle may occur with higher, than otherwise, loadswithout the bolts shearing and the continuous track units coming off thevehicle.

The recess may alternatively be formed within the surface of the secondportion.

FIG. 3 is a schematic of the situation where the wheel has been removedfrom the vehicle and been replaced by the first portion 40 attached tothe body of the vehicle 75 by means of bolts 44 located through aradially outwardly extending flange 42 at one end of the first portion.The first portion 40 is substantially cylindrical, other than for theflange, but has thickened walls at the axial end away from the vehiclebody 75. The first portion 40 extends axially as far as the disc 30.

The second portion 55 is shown for the sake of clarity.

The third portion 120 is shown attached to the disc 30 by means of bolts130. The third portion is also substantially cylindrical including anopen end axially distant from the vehicle body 75. The opposite axialend, closest to the disc 30, may also be open to reduce weight but has aradially inwardly extending flange 122 through which the bolts 130 maypass. At the open end, axially distant from the vehicle body 75, aradially outwardly extending flange 124 is provided to which an annulardisc 126 of the sprocket 140 is bolted 128.

The second portion 55 alternatively may be in the form of an annulardisc with the third portion 120 being attached to the drive hub/discthrough its open centre.

The apparatus may be arranged such that the third portion, or the secondand third portions, are removable from the vehicle so that the wheel isre-attachable to the drive hub with the first and second portions, orthe first portion, still attached to the vehicle. In this way, wheelsmay be re-fitted to the vehicle and then removed again and swapped fortrack units without the need to remove all of the apparatus from thevehicle.

The sprocket 140 is a standard, well known sprocket which includes bars142 (sprocket drive bars) which contact the inside of the continuoustrack (not shown) for driving it.

A standard sprocket 140 is shown in FIG. 4. An array of driver bars 142can be seen to extend around the circumference of the sprocket 140. Thebars 142 are attached together by two annular discs 126, 127 spacedaxially apart.

In use, the drive hub/disc 25, 30 will rotate, thus rotating the thirdportion and the sprocket.

FIG. 5 shows a portion of the third portion 120 whereby the axiallydistant outer flange 124 to which the sprocket 140 is attached may beseen. The annular disc 126 forming part of the sprocket 140 includesholes 129 through which bolts 128 pass to attach it to the flange 124.

The other annular disc 127 is also visible axially spaced above theannular disc 124. Some of the bars 142 are also visible extending out ofthe annular disc 127 perpendicularly.

With the first portion 40 attached to the vehicle body 75 the thirdportion 120 may be removed and the wheel 200 re-attached by bolts 130 tothe disc 30. This is shown in FIG. 6. The second portion may be presentbut if it is it will not hinder the attachment or rotation of the wheel200 as it does not extend far enough axially away from the end of thefirst portion 40 to interfere with the wheel 200. The wheel is shownwith a tyre 210 fitted.

In FIG. 7 an alternative arrangement is indicated. In this arrangementthe first portion 240 is substantially the same as the first portion 40described above in that it includes a cylinder having an outer uniformlysmooth wall and an internal bore which is stepped such that there is athinner walled section 241 adjacent the chassis 75 of the vehicle and athicker walled section 242 distal from the thinner walled section 241.

Bolts 244 are arranged via openings provided axially through the wall ofthe first portion 240. The bolts 244 extend through the chassis 75behind which nuts may be placed. Alternatively there may be tapped holesprovided in the chassis 75 into which the bolts may tighten.

The openings in the wall of the first portion 240 for the bolts 244 havea widened end distal from the chassis for the head of the bolt to restin. This widened portion 245 extends to the outer face of the firstportion 240 so that the bolts 244 may be inserted into the holes and foraccess to the head for tightening. The bolts 244 have their long axesparallel with the axis of rotation of the drive hub 25.

The second portion 250 in this alternative arrangement comprises a platehaving a hole therein (in other words an annulus) which is arrangedagainst the outer face of the first portion 240 such that the holematches with the bore of the first portion.

The second portion is affixed to the first portion using bolts 255 whichpass through the second plate and into threaded/tapped holes provided inthe outer face of the first portion. The bolts 255 have their long axesparallel with the axis of rotation of the drive hub 25. The holes forreceiving bolts 255 to attach the second portion 250 to the firstportion 240 are arranged approximately equidistantly and around thehole/bore. This ensures an even spread of any loading.

The drive hub 25 includes a rotatable part 26 including a disc 30 towhich the drive sprocket 260 is attachable. In the present example, thedrive sprocket 260 includes a cylindrical central portion 262 having abore with a long rotation axis parallel to the axis of rotation of thedisc 30. The central portion 262 has a flange 263 extending radiallyoutwardly at an end distal from the disc 30. At the end of the flange263 sprocket drive bars 264 are arranged having their long axes parallelwith the axis of rotation of the disc 30. These bars 264 contact theinside of the continuous track (not shown) for driving it.

At the other axial end of the cylindrical portion 262 a flange 261extends radially inward providing a surface which can be attached to theouter face of the disc 30 via bolts 130.

The drive sprocket 260 is similar to the one described in relation toFIG. 4. In this respect the feature referenced 120 is equivalent to thecylindrical portion 262, the feature referenced 126 is equivalent to theflange 263, and the bars referenced 142 are equivalent to the bars 264.

Not shown in FIG. 7 is the support arm 280 attached to this secondportion 250. However, with reference to FIG. 8 its position may beobserved to be below the disc 30 extending away from a lower portion 252of the second portion 250, below the hole through which the disc 30projects, in a direction substantially parallel with the rotational axisof the disc 30. The support arm 280 (or rocker arm) takes the form of acylinder. Gussets 253 are provided between the arm 280 and the secondportion's outer face to strengthen it.

Also shown in FIG. 8 is the disc 30 and central rotatable part 26, thebolts 130 for attachment of the drive sprocket (not shown) arrangedequidistantly around the disc 30, and the bolts 255 and holes foraccepting further bolts 255 for attaching the second portion 250 to thefirst portion 240.

The continuous track unit (not shown) is supported by the arm 280 and itmay at least partially rotate about it. The track unit may take the sameform as the one partially shown in FIG. 2.

The apparatus shown in FIG. 8 can be seen to be compact, lightweight andrelatively simple to attach to, and remove from, a vehicle.

In FIG. 9 part of a vehicle's chassis 325 is shown. A drive hub 330 isshown projecting from the chassis 325. Around the drive hub 330 amounting portion in the form of a plate 340 has been bolted via bolts345 to the chassis 325. The plate has been cut to so that there is noportion 342 above the drive hub 330 so as not to foul bolts 344 requiredfor other purposes by the vehicle.

The plate completely surrounds the drive hub 330 such that the hole doesnot reach the sides or edges of the plate 340.

A support arm 350 is shown extending away from the plate 340 in asubstantially orthogonal direction. The support arm 350 comprises acylindrical section having a uniform diameter which accounts for themajority of its length. Within the support arm 350 a pin 370 isarranged. The pin 370 is rotatable within, and relative to, the arm 350by means of bushings (not shown) arranged between them and internally ofthe arm 350. This pin 370 extends outwardly from the end of the arm 350distal from the chassis 325 and plate 340. At its most distal end, athreaded socket 372 is provided in the pin 370 for receipt of a bolt aswill be explained in more detail below.

The support arm 350 is attached to a plate 360 which is itself welded tothe mounting portion 340. Gussets 365 in the form of triangular platesare welded between the support arm 350 and the mounting portion 340 toprovide strength. One is shown lying in a vertical plane and one in ahorizontal plane.

The drive hub 330 includes bolts 335 projecting axially therefore forattachment of a drive sprocket.

FIG. 10 is a schematic of the situation where a wheel has been removedfrom a vehicle and has been replaced by the mounting portion 340(partially shown in broken lines around the wheel hub 330) attached tothe chassis 325 of the vehicle by means of bolts 345 located through theplate.

The support arm 350 is shown extending from the mounting portion 340.

A sprocket 380 is a standard, well known sprocket which includes bars386 (sprocket drive bars) which contact the inside of the continuoustrack (not shown) for driving it.

In use, the drive hub 330 will rotate, thus rotating the sprocket.

In FIG. 11 a portion of a differently shaped mounting portion 340 a isshown. This mounting portion is in the form a plate 340 a and isattached to the chassis (not shown) of the vehicle in a similar mannerto that described above. Also shown in FIG. 11 is a portion ofcontinuous track unit 315 attached to the vehicle via a support arm 350.It is seen that the pin 370 of the support arm 350 extends through theidler carriage 383 and includes a bolt 376 at its distal end screwedinto the threaded socket 372 to thereby retain the arm with thecarriage. FIG. 11 also shows the support arm 350 being arranged to fitinto an idler carriage 383 of a track unit comprising tie-bars 349,wherein the support arm 350 is arranged to replace an existing tie-bar349.

The carriage 383 comprises two parallel plates 352 between which idlers390 are rotatably supported. A portion of track 320 is also shown forclarity. The sprocket 380 is visibly bolted 335 to the drive hub 330.

In use, rotation of the carriage 383, and thus the track unit 315, aboutthe support arm 350 is limited by an abutting portion 351 of themounting portion 340 a abutting against an abutting portion 353 of thecarriage plate 352 closest to the chassis. Although not visible, similarabutting sides are arranged on the carriage 383 on the other side of thearm 350 and drive hub 330 from those shown.

The mounting portion 340 a and support arm 350 can be seen to becompact, lightweight and relatively simple to attach to, and removefrom, a vehicle.

While various embodiments of devices, systems, and methods have beendescribed in considerable detail herein, the embodiments are merelyoffered as non-limiting examples of the disclosure described herein. Itwill therefore be understood that various changes and modifications maybe made, and equivalents may be substituted for elements thereof,without departing from the scope of the present disclosure. The presentdisclosure is not intended to be exhaustive or limiting with respect tothe content thereof.

Further, in describing representative embodiments, the presentdisclosure may have presented a method and/or a process as a particularsequence of steps. However, to the extent that the method or processdoes not rely on the particular order of steps set forth therein, themethod or process should not be limited to the particular sequence ofsteps described, as other sequences of steps may be possible. Therefore,the particular order of the steps disclosed herein should not beconstrued as limitations of the present disclosure. In addition,disclosure directed to a method and/or process should not be limited tothe performance of their steps in the order written. Such sequences maybe varied and still remain within the scope of the present disclosure.

The invention claimed is:
 1. Apparatus arranged for converting a wheeledvehicle to a tracked vehicle by attachment of a continuous track unit,the vehicle comprising a drive hub which is arranged to have anattachable wheel, the continuous track unit replacing the wheel toengage ground in use for movement of the vehicle, the apparatuscomprising a mounting portion releasably attachable to a chassis of thevehicle, the mounting portion arranged to substantially surround thedrive hub, a support arm for supporting the continuous track unit, and adrive sprocket releasably attachable to the drive hub for transferringtorque from the drive hub to the continuous track unit so as to rotate atrack in use with the wheel removed and the apparatus attached to thevehicle, wherein the support arm is arranged to fit into an idlercarriage of the continuous track unit comprising tie-bars and to replacean existing tie-bar.
 2. The apparatus according to claim 1, wherein themounting portion comprises a flat plate for abutting against thevehicle's chassis when attached to the vehicle's chassis.
 3. Theapparatus according to claim 1, wherein the mounting portion comprisesthrough-holes for bolting it to the vehicle's chassis.
 4. The apparatusaccording to claim 1, wherein the mounting portion is attachable to thevehicle's chassis by fasteners which extend parallel with an axis ofrotation of the drive hub.
 5. The apparatus according to claim 1,wherein the mounting portion is attachable to the chassis by fastenersarranged circumferentially around the drive hub.
 6. The apparatusaccording to claim 5, wherein the fasteners are arranged approximatelyequidistantly around the drive hub.
 7. The apparatus according to claim1, wherein the mounting portion is in a form of a plate having anaperture therein extending to one edge of the plate, the drive hubprojecting through the aperture with the mounting portion fitted to thevehicle chassis.
 8. The apparatus according to claim 1, wherein thesupport arm is arranged such that it is off-set to one side of acentre-line passing vertically through the drive hub.
 9. The apparatusaccording to claim 1, wherein the support arm is arranged such that itis off-set towards a front of the vehicle in front of a centre-linepassing vertically through the drive hub.
 10. The apparatus according toclaim 1, wherein the support arm is arranged below the drive hub.
 11. Anarticulated wheeled vehicle including apparatus arranged for convertingit to an at least partially tracked vehicle by attachment of acontinuous track unit, the vehicle comprising a drive hub of the typewhich is arranged to have an attachable wheel, the continuous track unitreplacing the wheel to engage ground in use for movement of the vehicle,the apparatus comprising a mounting portion releasably attachable to achassis of the vehicle, the mounting portion arranged to substantiallysurround the drive hub, a support arm for supporting the continuoustrack unit, and a drive sprocket releasably attachable to the drive hubfor transferring torque from the drive hub to the continuous track unitso as to rotate a track in use with the wheel removed and the apparatusattached to the vehicle, wherein the support arm is arranged to fit intoan idler carriage of the continuous track unit comprising tie-bars andto replace an existing tie-bar.
 12. The vehicle according to claim 11,wherein the vehicle comprises two units articulated together with anarticulated joint, and comprising rigid drive axles such that steeringof the vehicle is effected by slewing the two units of the vehicle,separated by the articulation joint, relative to one another.
 13. Thevehicle according to claim 11, being arranged to lift and carry loads.14. The vehicle according to claim 13, being a loader, a fork lift, atele-handler, or a tool-carrier.
 15. The vehicle according to claim 11,comprising a movable arm.
 16. The vehicle according to claim 15, whereinthe movable arm is telescopic.
 17. The vehicle according to claim 11,having a weight less than 5 tonnes.
 18. Apparatus arranged forconverting a wheeled vehicle to a tracked vehicle by attachment of acontinuous track unit, the vehicle comprising a drive hub which isarranged to have an attachable wheel, the continuous track unitreplacing the wheel as the driving force of the vehicle, the apparatuscomprising a first portion attachable to a chassis of the vehicle, thefirst portion arranged to substantially surround the drive hub, a secondportion including a support arm for supporting the continuous trackunit, the second portion releasably attachable to the first portion, anda drive sprocket releasably attachable to the drive hub for transferringtorque from the drive hub to the continuous track unit so as to rotate atrack in use with the wheel removed and the apparatus attached to thevehicle, wherein the apparatus is arranged such that once attached tothe vehicle, the second portion and drive sprocket are removable, and awheel is attachable to the drive hub with the first portion stillattached to a support structure of the vehicle, wherein the support armis arranged to fit into an idler carriage of the continuous track unitcomprising tie-bars and to replace an existing tie-bar.